Mycosis Fungoides: A Case Report

Abstract

Mycosis fungoides is a rare T-cell lymphoma, but it accounts for about half of all cases of cutaneous 7-cell lymphoma. Radiation has long been used to treat patients with this radiosensitive disease. However, a significant proportion of patients present with generalized plaques or recurrence of lesions outside or even within the previously irradiated area, it challenged radiotherapists for decades how to irradiate skin (the superficial layer of a somewhat ”cylinder-like” human body) with not only larger field and higher dose but also tolerable toxicity. Radiation with low energy electrons generated by modern linear accelerators, depositing their energy within limited depth could spare deeper tissues. The six-dual-field technique, which provide more satisfying dose distribution for these requirements was developed at Stanford University three decades ago. Since then, the patients treated with total skin electron beam radiation would have better clinical response and minor toxicity. We adopted the six-dual-field technique to treat a 49-year-old male with generalized plaques. The source-to-surface distance was extended to be 323 cm, and an acrylic beam spoiler was installed to scatter the beam and attenuate the electron energy. The resulting electron energy was 2.62 MeV, generated by a 6 MeV Linac, the output of which was degraded to deliver 0.0648 cGy/MU (at the depth of maximum dose, d(subscript max). The collimator was fully opened to 40×40 cm^2 without a cone. The hinge angle of the dual-field was determined to be 20 degrees. The measured multiplication factor was 2.68. We prescribed a tumor dose at 5 mm depth beneath the skin surface (90% isodose profile). Overall, 1212 MU were required for each field. Beam flatness was within ±5% and ±10% in the vertical and horizontal dimensions, respectively. Thermoluminescent dosimeters (TLD) were used to evaluate dose homogeneity at 45 sites. Individualized boost or shielding was used at appropriate sites. Radiation therapy was administered for 4 consecutive days per week, with 2 days constituting a treatment cycle. On the first day of a cycle, half of the 6 dual-fields were irradiated, with the other half treated the other day A total dose of 36 Gy over 18 cycles was given with a fraction dose of 2 Gy. A 10-day midway break was given. The skin lesions responded well to this regimen, and itching was completely relieved prior to completion of the first half of the treatment course. Side effects (marked dermatitis of palms and soles and total hair loss) were acceptable. The patient refused subsequent adjuvant therapy. Despite total skin radiation can achieve good initial clinical outcome, the management of patients with mycosis fungoides is still challenging. This disease has a predisposition to relapse, and the chance is dismal to cure patients with the disease beyond limited plaque stage for the time being. In additicn to radiation therapy, a variety of modalities have been in clinical use or in investigation. We suppose combination treatment should be administered in these patients to improve long-term control.